Ladder-jack.



J. R. ANDERSON.

LADDER JACK. APPLICATION FILE-D Aue.4. 191's.

Patented June 5, 1917.

ATENT QFFTEQ JOHN R. ANDERSON, 0F MOLINE, ILLINOIS.

LADDERJ'AGK.

messes.

Specification of Letters Patent.

Patented June 5, 191 '7.

Application filed August 4, 1916. Serial No. 113,051.

To all whom it may concern:

Be it known that 1, JOHN R. ANDERSON, a citizen of the United States, residing at Moline, in the county of Rock Island and State of Illinois, have invented certain new and useful Improvements in Ladder-Jacks, of which the following is a specification.

This invention relates to a ladder ack and has for its object the provision of means applicable to a ladder of ordinary construction and readily adjustable thereon to support a stage or scaffold from which one or more workmen may operate.

A further object of my invention is the provision of a ladder jack which may be quickly adjusted and which automatically and securely locks itself to the ladder in the desired position to form a rigid horizontal support directed either inwardly or outwardly from the ladder.

Further objects and advantages of my in vention will be apparent as itis better understood by reference to the following specification when read in connection with the accompanying drawing, illustrating the preferred embodiment thereof, in which- Figure 1 is a side elevation of my invention applied to a ladder, a portion of which is illustrated in longitudinal section;

Fig. 2 is a section on the line 22 of Fig. 1;

Fig. 3 is an enlarged section on the line 83 of Fig. 1, and

Fig. 1 is an enlarged section on the line 1- 1 of Fig. 1.

Referring to the drawing, 1 and 2 inclicate, respectively, the longitudinal members, or legs, and rungs of a ladder of usual construction. Two or more jacks are employed and the jacks are constructed to cooperate with the right and left hand longitudinal members 1. Two ladders may be used in which case one or more jacks is applied to each ladder. As the right and left hand jacks are identical in construction and mode of operation the following description is limited to the single j ack illustrated in the drawing.

An elongated channel 3 embraces the outer edge of the longitudinal member -1 and is provided at either end with brackets 1 rigidly secured to the channel 3 and projecting beyond the inner edge of the longitudinal member 1. Pivotally mounted at 5 on the brackets at are upper and lower bell-crank levers 6 and 7, respectively, each having a cam face on one of its arms disposed to engage the inner edge of the longitudinal member 1.

Pivotally connected at 8 to the other arm of the bell-crank lever 7 is a bar 9 adapted to support a plank 10 forming the stage or scaffold. A chain 11 is connected to the free end of the bar 9 and adjustably engages a claw 12 on the free end of the bellcrank lever 6 to maintain the bar 9 at the desired angle relative to the longitudinal member 1.

A handle 13 is provided on the bell-crank lever 6 adjacent the claw 12 and a link 14 is pivotally connected at 15 and 16 to the bellcrank levers 6 and .7 so that the latter may be simultaneously operated to free the jack and adjust it longitudinally of the ladder. The bell-crank lever 7 is provided with an extension 17 having a foot 18 adapted to engage a rung 2 to insure against accidental slipping of the jack. The extension 17 and foot 18 are not, however, essential for the reason that the cam faces on the bell-crank levers 6 and 7 firmly grip the longitudinal member 1 and hold the jack in any position to which it is adjusted.

To utilize my invention the operator arranges a ladder, or two ladders if a longer stage is desired, against a building or other support and slips the channels 3 of the jacks over the outer or inner edges of the longi tudinal members 1. This is readily accomplished by grasping and swinging the handle 13 to turn the bell-crank levers 6 and '7 about their respective pivots. If the stage is to be arranged on the inside of the ladder the channels 3 embrace the outer edges of the longitudinal members 1 and if the stage is to be arranged on the outside of the ladder the channels 3 embrace the inner edges of the longitudinal members 3.

The jacks are then moved longitudinally of the ladder or ladders to the desired height and the handles 13 are released, the weight of the parts causing the cam faces of the bell-crank levers 6 and 7 to engage and force the longitudinal members 1 against the channels 3. The chains 11 are then adjusted in the claws 12 untilthe bars 9 are horizontal. The jacks can be instantly released and moved to a new position and as quickly locked thereon.

Ladder jacks constructed in accordance with my invention provide an inexpensive, safe and quickly adjustable means for suprangement of the parts without departing from the spirit and scope of the invention or sacrificing any of its material advantages, the form of my invention herembefore described being the preferred embodiment thereof.

I claim: I

1. A ladder jack comprising means to embrace one edge of a ladder leg, a member pivotally mounted on said means and having means thereon adapted to engage the other edge of said leg, a support for a stage or scaffold connected at one end to said'memher, and means connecting the free end of said support to the first mentioned means.

2. A ladder jack comprising means to embrace one edge of a ladder leg, a bell-crank lever pivotally mounted on said means and having a cam face adapted to engage the other edge of said leg, a support for a stage or scaffold pivotally connected to said bellcrank lever, and adjustable means connecting the free end of said support'to the firstinentioned means.

3. A ladder jack comprising means to embrace one edgeof a ladder leg, a member pivotally mounted on said means and hav ing a cam face adapted to engage the other edge of said leg and an extension to engage a run of the ladder, a support for a stage or sea old connected at one end to said member, andmeans connecting the free end of said support tothe first-mentioned means.

4. A ladder jack comprising means to embrace one edge of a ladder leg, a pair of members pivotally mounted on said means and having means thereon adapted to engage the other edge of said leg, a support for a stage or scafiold connected at one end to the lower of said members, and means connecting the free end of said support to the upper member.

5. A ladder jack comprising means to em brace one edge of a ladder leg, a pair of bellcrank levers pivotally mounted on said means and having cam faces adapted to engage the other edge of said leg, a support for a stage or scaffold connected at one end to the lower of said bell-crank levers, and means connecting the free end of said support to the upper bell-crank lever.

6. A ladder jack comprising means to embrace'one edge of a ladder leg, a pair of bell-crank levers pivotally mounted on said means and having means thereon to engage the other edge of said leg, a link connecting said bell-crank levers, a support for a stage or scafi'old connected at one end to the lower of said bell-crank levers, and means connecting the free end of said support to the upper bell-crank lever.

7. Aladder jack comprising means to embrace one edge of a ladder leg, a member pivotally mounted on said means and having means thereon adapted to engage the other edge of said leg, a support for a stage or scaifold connected at one end to said memmeans, and means on said bell-crank lever to engage a rung of the ladder.

9. A ladder jack comprising means to embrace one edge of a ladder leg, a pair of hellcrank levers pivotally mounted on said means and having means thereon to engage the other edge of said leg, a support for a stage or scaffold pivotally connected at one end to the lower of said bell-crank levers, a claw on the upper bell-crank lever, and a chain connected to the free end of saidsupport and adjustably engaging said claw.

10. A ladder jack comprising means to embrace the one edge of a ladder leg, a pair of bell-crank levers pivotally mounted on said means and having cam faces to engage the other edge of said leg, a support for a stage or scaffold pivotally connected at one end to the lower of said bell-crank levers, a claw on the upper bell-crank lever, a chain connected to the free end of said support and adjustably engaging said claw, a handle on the upper bell-crank lever, and a link connecting said bell-crank levers, whereby they may be simultaneously operated.

JOHN R. ANDERSON.

Witnesses:

Enro Larson, J. F. OHRBERG.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

